Thermal, Structural, AC Conductivity, and Dielectric Properties
dihydro-4H-pyrano[3,2-c]quinoline-3-carboxylate Thin Films
1.—Department of Physics, Faculty of Science, Damietta University, Damietta 34517, Egypt.
Thermal, structural, alternating-current (AC) conductivity (r
), and dielec-
tric properties of ethyl-2-amino-6-ethyl-5-oxo-4-(3-phenoxyphenyl)-5,6-dihy-
dro-4H-pyrano[3,2-c]quinoline-3-carboxylate (HPQC) thin ﬁlms have been
studied. Thermogravimetry analysis and differential scanning calorimetry
conﬁrmed the thermal stability of HPQC over a wide temperature range.
Fourier-transform infrared spectroscopy and x-ray diffraction analysis were
carried out on HPQC in powder form and as-deposited thin ﬁlm. The crystal
system and space group type were determined for HPQC in powder form. The
AC conductivity and dielectric properties were determined in the frequency
range from 0.5 kHz to 5 MHz and temperature range from 296 K to 443 K.
The AC electrical conduction of HPQC thin ﬁlm was found to be governed by
the small-polaron tunneling mechanism. The polaron hopping energy (W
tunneling distance (R), and density of states (N) near the Fermi level were
determined as functions of temperature and frequency. The dielectric prop-
erties of HPQC thin ﬁlm were studied by analysis of Nyquist diagrams, the
dissipation factor (tan d), and real (e¢) and imaginary (e¢¢) parts of the dielectric
Key words: Quinoline, thin ﬁlm, AC conductivity, small-polaron tunneling
mechanism, dielectric properties
Low cost and easy manufacturing are the main
reasons for use of organic materials in fabrication of
various electronic and photonic devices.
is an N-heterocyclic organic compound in which one
of the ring carbon atoms is replaced by nitrogen
The donor–acceptor (D–A) nature of the
main backbone of quinoline derivative has resulted
in great interest for use in the ﬁeld of organic
Moreover, simple modiﬁcations to the
donor or acceptor groups can change the physical
properties of the quinoline.
as organic biologically active compounds are
involved in various medical applications.
derivatives can also be used for synthesis of conju-
gated molecules and polymers.
They are charac-
terized by excellent mechanical properties,
high photoluminescence efﬁciency,
linear optical properties,
and good ﬁlm-forming
enabling signiﬁcant applications in
highly efﬁcient organic electronics such as optical
organic light-emitting diodes
dye-sensitized solar cells,
The physical, e.g., structural, thermal, optical,
photovoltaic, electrical, and dielectric, properties of
quinoline derivatives depend on the substitution
atoms or groups (i.e., electron-withdrawing group,
electron-donating group, and metal complex).
In our previous study, the effect of two different
donor substitution groups, namely chlorophenyl
(Ch-HPQ) and phenoxyphenyl (Ph-HPQ), on the
(Received December 16, 2017; accepted May 18, 2018)
Journal of ELECTRONIC MATERIALS
2018 The Minerals, Metals & Materials Society